Accumulation of potassium in scala vestibuli perilymph of the mammalian cochlea

Movements of potassium (K⁺) were monitored during perfusion of either the scala tympani (ST) or the scala vestibuli (SV) of the guinea pig cochlea with a solution containing 15 mmol/LK⁺. A highly asymmetric clearance of K⁺ was observed, with K⁺ rapidly being taken up from the ST and allowed to accumulate in the SV. Under some conditions the SV K⁺ concentration could exceed that in the perfused ST. These observations are believed to result from the distortion of passive K⁺ diffusion by the high circulating current of K⁺ that is part of the transduction process. Calculations are presented to demonstrate that circulating fluxes are of sufficient magnitude to generate the results observed. The high rate of circulating K⁺ current is probably also responsible for the difference in physiologic K⁺ concentration between the ST and SV, in which the ST perilymph K⁺ concentration is typically found to be half that of the SV. A clearance of K⁺ from the ST and its eventual accumulation in the SV could play a role in how the ear responds to abnormal ion concentrations, such as may occur in Meniere’s disease. It is proposed that an accumulation of K⁺ in the SV would result in vestibular dysfunction that might contribute to the vestibular symptoms of the disease.